VATICAN CITY, Oct 6 (Reuters) - Pope Francis has ordered a "thorough study" of all documents in Vatican offices concerning disgraced former U.S. Cardinal Theodore McCarrick, in the Holy See's first response to accusations raised against the pontiff in the case.

In a document released in August, Carlo Maria Vigano, the Vatican's former ambassador to the United States, said the pope knew for years about sexual misconduct by McCarrick with adult male seminarians but did nothing about it.

McCarrick in July became the first cardinal in living memory to resign from his position in the Church leadership after a separate review concluded that claims he had sexually abused a 16-year-old boy were credible. (Reporting by Philip Pullella; Writing by Agnieszka Flak; Editing by Hugh Lawson)